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From: tls@panix.com (Thor Lancelot Simon)
Newsgroups: comp.dcom.telecom
Subject: Re: Does FiOS support rotary phones? [telecom]
Date: Thu, 28 Apr 2011 15:55:57 +0000 (UTC)
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In article <ipbu08$72m$1@reader1.panix.com>,
Thor Lancelot Simon <tls@panix.com> wrote:
>
>not know but would tend to speculate likely not.  I believe there
>is really, truly, a 300 fiber bundle running in from the street and
>that it's not actively multiplexed until that location.  Maybe
>there are totally passive ways to do DWDM now so the passive "hubs"
>in the building actually have unpowered frequency multipliers/dividers
>in them -- I do not know.

I have looked into this a bit more; the above is not really correct in
two important respects.

1) The fiber "hubs" used by Verizon appear to be passive optical
   beam splitters/combiners.  The network is fully broadcast for
   downstream communications with a link layer beneath any standard
   Ethernet framing that emulates point-to-point Ethernet behavior
   (it would certainly seem that since there is a single downstream
   transmitter collisions really aren't possible so this should not
   be hard).  Downstream transmissions are encrypted so that, in theory,
   only a specific ONT can decrypt them.

   Upstream is a little funny.  The upstream signal supposedly
   propagates only towards the head end (how this is done optically
   I do not know but I'm sure it's possible), so encryption is not
   used.  I don't know how the head end handles collisions though
   it appears TDM in the upstream direction is used to attempt to
   assure they do not occur.

2) Fully passive DWDM/CWDM equipment is, in fact, available from several
   suppliers, but use of it in a PON deployment such as FiOS would be,
   at least, not something that is standardized.

So, the diagram I have that shows VZ entering the building in question
with two fibers -- not 300 -- is almost certainly correct in that detail,
and I was speaking whereof I knew not.

-- 
Thor Lancelot Simon	                                         tls@panix.com
    And now he couldn't remember when this passion had flown, leaving him so
  foolish and bewildered and astray: can any man?
						   William Styron